Compound metal stock



1940- F. P.- HUSTON ET AL 2,225,868

COMPOUND METAL STOCK Y Original Filed Nov. 7, 1933 2 Sheets-Sheet 1 BASEMETAIY 6 PRQTECTIVE METAL W; 8 WELDS Big/E METAL I PROTECTIVE METALHROMIUM ALLOY 9 IALLOYBOND INVENTORS FREDERICK P HUS To/y BYfi/YDREWWESL 5r Pt-w w NEY 'F. P. HUSTON ETAL I COMPOUNDMETAL s'rocx Dec- 24,

Original Filed Nov. 7, 1933 2 Sheets-Sheet 2 IN ENTORSFREDEfi/C/IPHZ/STO/Y A TORNEY Patented Dec. 24, 1940 UNITED STATES2,235,868 COMPOUND METAL STOCK Frederick P. Huston, Fanwood, and AndrewWesley, Plainfleld, N. J., assignors to The International NickelCompany, Inc., New-York, N. Y., a corporation of Delaware Originalapplication November 7, 1933, Serial No.

696,946, now Patent No. 2,147,407, dated February 14, 1939.

Divided and this application December 21, 1938, Serial No. 246,946

'9 Claims.

The present invention relates to cladded metal products containingchromium, and more particularly to composite metals integrally unitedand having a'portion containing chromium.

Heretofore various methods have been proposed for the production ofcladded metalproducts, especially cladded metal products in which thebase metal or the cladding metal contains chromium. These prior methodsinvolved certain disadvantages and produced product having shortcomingsand/or defects. One of the worse disadvantages of prior cladded productscontaining chromium was that the cladded product could not be subjectedto certain stresses and certain operations without the cladding metaltearing from the base metal. For instance, the bending and particularlythe twisting of prior cladded products containing chromium tore thecladding metal from the base metal. Although the art was struggling fora solution to the outstanding problem, none as far as we are aware, waswholly successful and produced a completely satisfactory product.

We have discovered a method of producing cladded metal productscontaining chromium which is free from the disadvantages andshortcomings noted hereinabove and which is capable of producingsatisfactory, successfully and commercially acceptable compositeproducts.

It is an object of the invention to provide a cladded metal productcontaining chromium which can be bent and twisted without falling andwithout coming apart.

It is also within the contemplation of the invention to provide acladded metal product containing chromium which consists of a backing orbase metal which is relatively cheap or which has some desirableproperties not possessed by the surface coating and a cladding metal oralloy which may be used to cover one or both surfaces of the base metalor alloy which contains chromium and which has superior corrosion and/orheat resisting properties.

Other objects and advantages of the invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings, in which:

Fig. l is a sectional view, somewhat diagrammatic of a pack of platesto'be bonded by the present method;

Fig. 2 is a diagrammatic illustration, somewhat exaggerated, of aphotomicrograph of a Generally speaking, the present discoverycontemplates the provision of a film containing nickel or a nickel alloyto envelope or to coat the metal or alloy containing chromium. Byincorporating the foregoing provision in the process of producingcladded metal products, it is possible to produce such products on anindustrial scale readily and uniformly. The complete explanation ofhowthe nickel film functions in the production of a satisfactory andsuccessful composite product containing chromium has not been definitelyestablished. -As a theory, we believe that the nickel or nickel alloyforms a bond having high physical properties by partial interditifusioninto not only the chromium containing metal or alloy but also into thebase metal especially during the subsequent hot working operations, andthat the nickel film protects the surface of the chromium-containingalloy when it is heated. It is to be noted that the foregoing is merelyadvanced as a theoretical explanation of the success of the presentmethod, but it is to be understood that if such explanation is found tobe incorrect, it is to be disregarded.

Broadly stated, the invention contemplates the production of a claddedmetal product containing chromium which comprises a base metal or alloy,a cladding or coating metal or alloy containing chromium and anintermediate layer or film containing nickel or a nickel alloy which isadhesively united to the entire face of said chromium-containingcladding metal to form an integral unit. In carrying the invention intopractice, the surface of the chromium containing metal or alloy isadhesively coated with a film of nickel or a nickel containing alloy andthe base metal having a clean surface is contacted firmly against thefilm of nickel and the two base metal and cladding metal are securedtogether in some appropriate manner as by clamping, weighting, welding,or the like. The composite product is then heated to a relatively hightemperature preferably in a reducing atmosphere. If a stack of layersare piled on each other, the weight thereof may be suflicient to causethe base metal to stick to or bond with the film of nickel on thechromium-containing cladding plate or sheet. In some cases, a heavyweight on the stack may be used to effect the sticking or bonding of thesheets. In the event 6 that a composite product like the one shown inFig. 1 is being made, hot working such as rolling, forging or the likemay be employed. The heated composite product is then subjected toworking operations such as forging, rolling or the like. After thebonding of the various layers has been accomplished not only hot workingbut also cold: working may be employed. In the finished product the basemetal or alloy and the cladding or coating metal or alloy are integrallyunited so thoroughly and effectively that the product can be stressedand deformed severely without rupturing the bond between the base andthe coating. It is to be noted that the new composite product isparticularly valuable where the product is to be used in structureswhich are subjected to severe stresses or where the product is to besubjected to severe fabricating operations. For instance, the improvedproduct even in its reduced or worked condition can be twisted into ahelix or the like without the cladding metal tearing away from the basemetal.

For the purpose of giving those skilled in the art a betterunderstanding of the invention the following specific example is givenfor the purpose of illustration.

A plate which is composed of chromium-nickel alloy and which is of aninch thick and of any desired length and width is cleaned in anyappropriate manner, such as by sand blasting, pickling or the like. Inthis manner, a clean and scale-free surface isproduced. To this cleanedsurface a film of nickel or of a nickel alloy is applied. Theapplication of the nickel film may be effected, for instance, byelectroplating or by 40 metal spraying or by any other suitable process.

In practice, it is preferred to apply the film of nickel or nickel alloyby means of electrodeposition. In the event that only one surface of aplate is to be cladded, it is preferred to 4 place two equal sizedplates back to back and secure them together by means of suitable clampsor the like. The clamped plates which may be constituted of a chromiumcontaining metal or alloy such as a chromium nickel alloy, is im- 9mersed in an electrolyte having a suitable com. position for theelectrodeposition of nickel or of a nickel alloy.

A film, coating or layer of nickel or nickel alloy is electrodepositedupon the cleaned surfaces 55 of the plates arranged back to back. Theelectrodeposition is conducted in any appropriate manner to yield adense, adherent deposit of a nickel or nickel alloy. For instance, thechromium containing plates may be cleaned in the 60 usual manner bytreating them as cathodes in an electrolytic alkaline cleaning bath.After this operation. the plates are rinsed in hot water and are.immersed in a solution of muriatic acid containing 5% by weight ofhydrochloric acid and heated to a temperature of about 156 F. They areheld in the acid solution for several minutes which removes oxide orother surface films of a type tending to interfere with welding by heatand pressure and are then transferred directly to a nickel plating bathwhere the coating of nickel is electrodeposited. The nickel coating isthus deposited on a cleaned surface of the chromium containing plate andprotects said surface against reformation of oxide or other 7 surfacefilms that would interfere with welding aaaaaos It is preferred to usethe following nickel plating solution and the following operatingconditions:

Temperature 130 to 150 F. Agitation Moderate air agitation Currentdensity amp. per sq. ft. Nickel sulphate 44 oz. per gallon Nickelchloride 2.2 oz. per gallon Boric acid 4.0 oz. per gallon Sodiumsulphate (anhydrous) 13.8 oz. per gallon The nickel coated platescontaining chromium are assembled in one composite pack orbillet whichmay have any suitable arran ement. A satisfactory assembly of the packis diagram matically illustrated in Fig. 1 of the drawings.

.Steel slabs i and 6 which have a thickness of about 3%" and of slightlygreater width and length than the nickel plated chromium containingplates have at least one surface cleaned in an appropriate manner suchas machining, sand blasting, grinding or the like. In this manner, adry, grease-free, clean steel surface is obtained.

In setting up the stack or pack, it is preferred to lay steel slab Iflat upon the floor with its clean surface facing upwardly. Upon steelslab l is placed the chromium containing plate 2 with the nickel coatedsurface 3 in contact with the clean surface of steel slab I. A secondchromium containing plate 4 is laid upon the first chromium containingplate 2 with its nickel coated surface 5 exposed upwardly. Upon thenickel coated surface, a second steel slab 6 is Of course, the thicknessof the film or placed with the clean surface in contact with the nickelcoated surface 5. In practice, it is preferred to use welds I to securethe steel plates to the chromium-containing plates and to use welds 8 tosecure the chromium-containing plates together. as may be clearly seenin Fig. 1. It is to be noted, however, that these welds shouldpreferably be discontinuous and should be disrupted at one or morepoints to provide vents in \order to permit the escape of the expandinggases.

In the foregoing manner, a composite pack or billet is formed in whichthe clean surface of the steel slab and the nickel coated surface of thechromium containing plate are held together. The composite pack isheated to a temperature suitable for bonding. In the present instancewhere a steel slab is being cladded with a plate of an alloy of chromiumand nickel, a temperature of about 2000 F. to about 2300 F. ispreferred. The heating is effected preferably in a reducing atmosphere.When the entire pack has reached this temperature it is hot worked in anappropriate manner, as for example, hot rolled. It has been found thatonly a small amount of hot working is necessary to secure a good bondbetween the steel slab and the nickel coated plate containing chromium.In other instances, however, it has been found that a great reductiontrimmed. In this manner, two cladded steel,

products are produced each of which are about of an inch in thickness.The cladding is equal to about of the total thickness. Of course, theamount of. cladding can be varied depending upon the particularconditions. For most practical purposes, the thickness of the claddedmetal is from five to twenty per cent of the total thickness, dependingon the thickness of cladded metal needed to withstand the particularconditions of corrosion, abrasion, scaling, etc.

In Fig. 2 a diagrammatic illustration of a photomicrograph of theproduct produced in accordancewith the. foregoing method is depicted. Itwill be observed that the reference character 9 depicts a portion of thealloy of chromium nickel and reference character I0 depicts a portion ofthe steel layer. Between the two layers 9 and III is an intermediatelayer l I constituting the nickel coat. Between the nickel layer and thesteel layer is a bond l3. In the same way, between layer 9 and II is abond l2 constituting an oxidefree diffusion zone of the metal of thelayer 9 in the protective layer II. It was found that the productproduced in accordance with the present method could be subjected tosevere stresses and could be subjected to various fabricatingoperations. Not only could the product be subjected to stresses andfabricating operations, but it could also be subjected to intensebending and twisting without the cladding metal tearing from the baseplate of steel or without the bonds rupturingor failing in .any way. Asa result of practical tests it has been found that the present productcan be produced on an industrial scale and the product usedcommercially.

Under certain conditions, it may be desired to heat a multiplicity ofcomposite products at one time. For instance, if it is necessary toobtain a. large production from a furnace in a short period of time,then it is preferred to use the arrangement shown in Fig. 3. In thisfigure, the reference character K designates a metal container whichcompletely encloses the composite products to be bonded. In practice, itis preferable to employ sheet metal, such as sheet steel, for containerK because of its light weight, its ability to expand freely, its lowcost, its adaptability for folding, welding, etc. and its easy' cuttingproperties. Of course, the conventional containers or boxes of castmetal or alloy may be used, if desired.

It is to be observed that chromium containing plates 2 and 4 do not weldto each other because their contacting surfaces have not been nickelcoated. Moreover, it is preferred to leave the surfaces of plates 2 and4 which are to be plated back to back in an uncleaned condition.Furthermore, the surfaces placed back to back can be coated with somerefractory material or the like which will eliminate all possibility ofplates 2 and 4 being stuck together mechanically or otherwise.

It is to be noted that the present invention prothe chromium containingcladding, and that the composite metal possesses overall propertiessuperior to either the solid base metal or alloy, or the solid coatingor cladding metal or alloy. For example, stainless steel cladded copperwould have the corrosion resistant of stainless steel but would have aconsiderably greater heat conductivity than stainless steel.

A stack of plates maybe arranged as shown in Fig. 3 with .achromium-containing plate C at the bottom. This plate is placed so thatthe nickel film N faces upwardly. Upon the nickel fllm, a steel plate Sis mounted. A second chromiumcontaining plate C with a nickel film Nfacin downwardly engages the top of steel plate S. This stack of platesis herein termed a set.

As many sets as desired may be stacked up. A sheet of steel may then befolded around the stack and secured togetheras by welding or the like.-In order to completely enclose the stack, end portions of sheet steelmay be welded to the open ends of the folded sheet. For the purpose ofpermitting the escape of gas from the welded container, a vent V may beprovided, preferably in the top of the container.

That stack of sets enclosed in the container is heated sufficiently highto effect bonding of the nickel to the adjacent faces of the steelplates. Due to the fact that the stack is sealed in a container, theheating is practically independent of the furnace atmosphere. If theweight of the stack is heavy enough, the nickel will be stuck or unitedto the steel. Usually, it has been found sufficient to press down on thetop of the stack. For instance, a heavy plate, weight or the like may beplaced on the top of the stack or the stack may be placed in a hydraulicpress. After this each unit set may be subjected to working operations,such as hot or cold rolling, forging, etc. When the units have beenworked or reduced to the desired extent, the cladded product is readyfor fabricating operations to convert the same into articles ofmanufacture.

In the foregoing operations, it has been found that the bottom and topplates of chromium-containing material do not stick 'or bond to theadjacent walls of the enclosing container or stick together. It appearsthat a greenish scale is formed on the chromium-containing plates whichprevents sticking or bonding. The composite units comprising a steelbase plate having a nick el coated cladding plate containing chromium oneach face of the steel plate may be taken from the stack and handled ortreated separately. Under the influence of the conditions within thecontainer including heat, pressure and atmosphere, a. diffusion bond iseffected between the nickel and the chromium-containing plate, In thismanner the two chromium plates and intermediate steel plate are unitedinto an integral double cladded unit, of course, the integraldouble-cladded units may be removed from the container by opening thesame in any appropriate manner. If a container made of sheet steelv isused, it can be easily cut apart and the stack of sets may be easilyremoved therefrom.

In the event that it is desired to single clad a metal or alloy, such asa steel plate, sheets or the like, an arrangement such as illustrated inFig. 4 may be employed.

Within container K and at the bottom thereof, a chromium-containingplate C is placed with the surface bearing chromium in contact with thesurface of the container which may besteel. The surface of the nickelfilm or layer N of the chromium containing plate faces upwardly. Uponthe nickel film or layer N, a steel plate 8 is mounted. Of course, thesurface of the steel plate S, which makes contact with the nickel, is

5 thoroughly cleaned as explained herelnbefore. A chromium-containingplate and a steel plate with a nickel film intermediate thereof isherein termed a single clad unit.

By placing a plurality of single clad units in i container K, the lattermay be filled and may then be closed as by welding or the like. A vent Vis preferably provided to permit the escape of gases from the containerK during heating operations.

15 In the event thatit is desired, it is preferred to insert a separatorbetween the top of the steel plate of any unit and the bottom of thechromium-containing plate of the next higher unit which makes contactwith the steel plate. It has 20 been found that one or more uncleanedsheets of chromium-containing material function satisfactorily as aseparator. Of course, a layer of refractory material may likewise beused as a separator instead of the uncleaned sheets.

25 When the container is charged with single-clad unitt and is sealed,it may be introduced into a furnace and heated to a temperature of atleast about 1800 to 2000 F. and preferably 2300 F. for a period of atleast about /2 to 2 hours. In

30 other words, the container is subjected to heat and pressuresufficient to insure the bonding of the steel plate to the nickel filmor layer and of the latter to the chromium-containing plate to form anintegral unit. The container may then 35 be opened and each unit may besubjected to working, as rolling, forging and the like. By applying thedesired amount of working, an appropriate reduction of area may beeffected and the unit may be reduced to the desired size. The

40 final product is a single clad unit which has such a tenacious bondthat a sample of about inches long may be subjected to a twisting testwhich involved twisting the sample through 360 degrees and thenretwisting the sample to its origi- 5 nal condition without the bondrupturing.

It is to be further noted that in the present instances the chromiumnickel alloy contains 14% of chromium, 6% of iron and 80% of nickel butother chromium-containing alloys may be 50 substituted therefor. Thus,for instance, any of the stainless steels, particularly those containingabout 18% of chromium and about 8% of nickel may be used and steelcladded products made with a clad of stainless steel may be produced.

55 Similarly, copper or other metals or alloys containing little or nochromium can be substituted for steel to produce a composite producthaving a base of copper or the like and a cladding of achromium-containing alloy.

60 It is also; to be observed that the composite product can besubjected to the same fabricating operations as would be employed on asheet or plate composed of the base metal. The composite product withsteel as the base metal can be 65 worked either hot or cold by spinning,pressing, drawing, flanging, bending, dishing, hammering, etc., and bythe usual cold working operations such as shearing, punching anddrilling; joining by riveting, welding, lock-seaming, soldering, etc.

70 It is preferred to cold work the composite product clad on copper asa base, and it may be subjected to spinning, stamping, drawing,pressing, fianging, joining, etc.

Furthermore, it is to be noted that the addi- 75 tion of the bondedlayer of chromium containing alloy to mild steel, copper, etc. givesadded strength to the base metal and enables the composite product to bemore highly stressed in tension, compression, or shear than would besafe with a plate or sheet of the solid base metal. 5 Moreover, thearticles of manufacture which can be produced from the composite productinclude autoclaves, kettles, dye vats, soap boiling equipment, dairytanks, truck tanks, beer fermenting and storage tanks, cooking utensils,and 10 other equipment for the chemical, dairy food products, and alliedfields, and the home.

Itis to be noted that the present invention is not to be confused withproposed processes in which a separate sheet of iron is laid between asteel plate and a chrome alloy plate. In this proposed process, it isnecessary to provide. special means in order to produce a bond for unionbetween the various parts. Thus, a deoxidizing agent such as an aluminumpowder or the like must be provided in order to dissipate oxygen gaseswhich are present in the air spaces between the steel plate and theintermediate iron sheet and between the chrome alloy plate and the ironsheet. Furthermore, various fluxes have been proposed to facilitate thebonding of the various sheets and plates or the like. The presentinvention avoids the foregoing complicated process and provides aprocedure which produces reliably, consistently and uniformly coatedproducts with a tenacious bond throughout the interface of theconnecting surface of the plates or the like which are to be joinedtogether.

Although the invention has been described in conjunction with preferredembodiments, it is to be observed that modifications and variations maybe resorted to as one skilled in the art can readily understand. Thus,various modifications can be made in the individual steps of the novelprocess and the invention can be applied 40 to the production of coatedwire, tubes, rods and the like by altering the shapes of the partsconstituting the composite pack or billet.

Of course, equivalents of nickel or nickel alloys such as cobalt, ironand the like, may be employed provided the metal or alloy is adhesivelyunited to the entire surface of the chromium-containing plate or thelike in order to form an impervious protective film. For adhesivelyuniting the nickel or nickel alloy or equivalent metal or alloy to theface of the chromiumcontaining plate, electroplating, spraying by theSchoop process, or the like may be utilized.

The present application is a division of our co-pending applicationSerial No. 696,946, filed on November 7th, 1933, which has now maturedinto Patent No. 2,147,407, dated February 14, 1939, and having the titleMethod of producing composite metals.

We claim:

1. A composite metal mass comprising a portion consisting of a fen'ousalloy containing sufficient chromium to interfere substantially withwelding by heat and pressure, an oxide-free diffusion zone adjacentthereto comprising a solid solution of metal of such chromium containingalloy in electrolytic nickel deposited in situ and additional metalmerging into such electrolytic nickel andunited thereto by welding.

2. A composite metal mass comprising a facing of corrosion-resistantmetal, electrolytic nickel deposited thereon and diffused therewithsubstantially without intervening oxide and a backing of ferrous metalwelded thereto.

3. A cladded metallic product which comprises 75 a base metalQa clad ofalloy comprised largely of metal selectedfrom the group consisting ofiron and nickel containing suflicient chromium to form a surface filmtending to interfere with welding by heat and pressure, and a film ofprotective metal intermediate and interposed between said base metal andsaid alloy and being electro-deposited on said alloy, said protectivemetal being integrally bonded to said base metal and to said alloysubstantially without interfering film to form an integral unit;

4. A cladded metallic product which comprises a base of copper, a cladof alloy comprised largely of metal selected from the group consistingof iron and nickel containing sufflcient chromium to form a surface filmtending to interfere with welding by heat and pressure,and a film ofnickel intermediate between said copper and said alloy and beingelectrodeposited on said alloy, said nickel being bonded to saidcopperand to said alloy substantially without interfering film to form anintegral unit.

5. A cladded metallic product which comprises a base of ferrousmaterial, a clad of nickel alloy containing suflicient chromium tointerfere with welding by heat and pressure, and a film of nickelintermediate and interposed between said ferrous material and said alloyand being electrodeposited on said alloy, said nickel being l bonded tosaid ferrous material and to said alloy substantially with theinterfering film to form an integral unit.

6. A cladded metallic product which comprises a base metal, a clad ofchromium-containing alloy having a face bonded to said base metal andcomprised largely of metal selected from the group consisting of ironand nickel containing sufllicent chromium to form a surface film tendingto interfere with welding by heat and pres- 40 sure, and afilm ofprotective metal intermediate and interposed between said base metal andsaid alloy and being integrally incorporated as particles on said alloyto cover entirely the aforesaid face thereof, said protective metalbeing in- 5 tegrally bonded to said base metal and to said alloysubstantially without interfering film to form an integral unit capableof being subjected to bending and twisting tests without the clad ofchromium-containing alloy separating from 50 the base.

7. A cladded metallic product which comprises a base of copper, a cladof chromium-containing alloy having a face bonded to said base metal andcomprised largely of metal selected from the group consisting of ironand nickel containing sufficient chromium to form a surface film tendingto interfere with welding by heat and pres sure, and a film of nickelintermediatebetween said copper and said alloy and being integrallyincorporated as particles on said alloy to cover entirely'the aforesaidface thereof, said nickel being bonded to said copper and to said alloysubstantially without interfering film to form an integral unit capableof being subjected to bending and twisting tests without the clad ofchromium-containing alloy separating from the base.

8. A cladded metallic product which comprises a base of ferrousmaterial, a clad of chromiumnickel alloy having a face bonded to saidbase and containing sufficient chromium to interfere with welding byheat and pressure, and a film of nickel intermediate and interposedbetween said ferrous material and said alloy and being integrallyincorporated as particles on said alloy to cover entirely the aforesaidface thereof, said nickel being bonded to said ferrous material and tosaid alloy substantially without interfering film to form an integralunit capable of being subjected to bending and twisting tests withoutthe clad of chromium-nickel alloy separating from the base.

9. A cladded metallic product which comprises a base metal, a clad ofchromium-containing alloy having a face bonded to said base metal andcontaining sufficient chromium to form a surface film tending tointerfere with welding by heat and pressure, and a film of. protectivemetalinttermediate and interposed between said base metal and saidchromium alloy and being integrally incorporated as particles on saidalloy to cover entirely the aforesaid face thereof, said protectivemetal being integrally bonded to said base metal and said chromium alloysubstantially without interfering film to form an integral unit capableof being subjected to bending and twisting tests without the clad ofchromiumcontaining alloy separating from-the base.

\ ANDREW WESLEY.

FREDERICK P. HUSTON'.

